Author Archives: Andi

What are Flash SSDs?

Earlier we used traditional hard disk drives in our computers. These were mechanically spinning magnetic disks with read-write heads. Nowadays, we use SSD or Solid-State Drives that have no moving parts. SSDs can retain data once it is saved without power, as they use NAND flash memory. To increase the data density, the NAND chips are multilayered. That means they can hold upwards of one bit of information per cell. SSDs using multilayered chips are named single-, multi-, triple-, quad-, and penta-level SSDs, according to the number of bits each cell can hold.

Multilayered SSDs have their own advantages and shortcomings and can range from speed to price to reliability. For instance, SLC or Single Level Cells have a lifespan measured in program/erase cycles of about 50,000 to 100,000 and can withstand high-intensity write operations.

MLCs or multi-level cells with two bits per cell can expect a lifespan of about 10,000 cycles and are mostly suitable for enterprise data centers.

TLCs or triple-level cells with three bits per cell can expect a lifespan of about 3,000 cycles and are useful for digital consumer products.

QLCs or quad-level cells with four bits per cell can expect a lifespan of about 2,000 cycles and are suitable for read-heavy operations, streaming media, and content delivery applications.

No data is available for the lifespan of PLCs or penta-level cells with five bits per cell. These SSDs are suitable for long-term storage of data such as in data archives.

Flash SSDs have revolutionized the storage of enterprise data in all its forms. They have enabled faster boot times and the application starts on PCs and mobile devices. They have facilitated the blistering performance of storage arrays in workloads like business analytics. In most performance metrics, flash SSDs have far outshone the older hard disk drives.

Speed aside, flash SSDs offer additional benefits. They are far more durable while being less susceptible to damage from abrupt physical shocks and movements, as compared to the traditional HDDs. Additionally, they use much less power to operate. Even though they cost more than the HDDs per gigabyte, the improved performance of SSDs overcomes their higher expense for most applications.

Flash SSDs store data in their memory cells using a technique called FGT or Floating Gate Metal Oxide Field Effect Transistors that can store a binary 0 or 1. With two gates, each FGT behaves like an electrical switch with current flowing between two points. NAND flash is named so as it uses NOT-AND logic gates. Power is not necessary to retain data in the flash cells, as, in the absence of power, the FGT provides the electrical charge for maintaining the data intact in the memory cells.

Flash SSDs are solid state, meaning they have no mechanical part to wear out. However, SSDs can nonetheless fail. One measure of SSDs is the lifespan or the number of program/erase cycles that a drive can complete before its degradation and failure. This is overcome by using wear-leveling technology, whereby the life of the SSD is prolonged by evenly distributing the program/erase cycle across the total NAND cells in the drive.

New Circuit Protection Technologies

A wide variety of vehicle models is entering the EV market these days. The demand is for decreased charging times and increased range. This is heightening not only the challenges towards electrical system performance but also towards better circuit protection.

For instance, decreasing the charging times requires systems using higher voltages and higher currents. This has necessitated the shift from the 400 V system to the 800 V, bringing with it major challenges to the design of circuit protection, especially on the battery side. That is because manufacturers must now consider increased fault currents that the protection components must handle.

With motor currents and power ramping up, circuit protection and switching devices also face higher stresses. They now need to withstand not only the higher operating currents but also the higher cycling requirements. Increased range means higher fault currents.

Therefore, circuit protection requirements are moving in several directions simultaneously. SiC MOSFET switches, acting as solid-state resettable transistor switches, address the high-voltage, low-current subsystems.

The power distribution box in the vehicle is still using the conventional system architecture of a coordinated fuse and contactor. Coordination between the two is necessary to ensure they cover the full range of possible faults from a range of underlying causes including different states of charge of the battery.

Another circuit protection technique is the pyrotechnic approach. This comes into play in events of a catastrophic nature, such as in crashes, when it is necessary to physically cut the busbar. These systems are mostly triggered by circuits that deploy the airbag and work to quickly isolate the battery from the rest of the vehicle. This helps to protect the driver, the passengers, and the first responders from fire and explosion from short circuits through the body of the vehicle.

The above are leading to the development of newer types of protection, such as with breaktors, fully coordinating circuit protection, and switching. Its design allows the breaktor to trigger passively or it can actively interrupt in case of power loss, thereby improving the functional safety of critical protection systems. Moreover, it has the ability to reset itself.

Another is an automotive precision bidirectional eFuse, which is increasingly becoming a common device in a vehicle. Traditional automotive fuses can be low in accuracy and slow to react. This can be a safety issue, as the safety of the system is indirectly proportional to the response time of a fuse. An eFuse not only has high accuracy but also a low response time, which increases the safety of the system.

However, there is a durability issue related to fuses and contactors that vehicle manufacturers use. The solution for this is the pyrotechnical switch. This is a protection device based on a trigger-able circuit similar to the functioning of an airbag. It produces a controlled explosion to sever a conducting busbar. Pyrotechnical switches, while solving the challenge of coordination, must rely on accurate triggering rather than on the passive reaction of fuses. Additional components are necessary to ensure a reliable triggering.

All the above protection systems require a trade-off between speed and durability. While a big fuse can be slow to operate, a smaller one may be faster but may suffer from a fatigue risk.

FIR Temperature Sensor

Among the many things that the COVID-19 pandemic taught us was the technique of assessing the human body temperature non-invasively. This was used in several locations, including hospitals, schools, and airports, employing an infrared sensor for measuring the surface temperature without making physical contact. Now, this is a popular method used commonly for taking body temperature. While being non-invasive, infrared thermometers also provide quick and reliable readings.

The accuracy of the infrared thermometer technique was affected by variables including the nature of the surface under measurement and its surroundings. However, scientists have largely resolved these issues, attaining medical-grade accuracy and compensation. In the process, they have also successfully lowered the size of the thermometer. Accordingly, Melexis Microelectronic Integrated Systems have developed a miniature infrared temperature sensor.

Based in Belgium, Melexis specializes in ICs and microelectronic sensors for applications involving consumer, automotive, digital health, smart devices, and energy management. For instance, Samsung is using one of Melexis’s products, the MLX90832 temperature sensor that works on FIR or far-infrared technology, for their GW5 smartwatch. The medical-grade version of the Melexis temperature sensor allows menstrual cycle tracking. Such continuous but reliable temperature monitoring opens up a vast range of newer applications in health, sports, and other domains.

The FIR sensor from Melexis is an SMD or surface-mount device that can accurately measure an object’s infrared radiation to record its temperature. The SMD packaging makes the sensor suitable for a large variety of applications, such as wearables, including hearables or in-ear devices, and point-of-care clinical applications that require highly accurate human-body temperature measurement.

Non-contact temperature measurement has several advantages over the more traditional contact methods. It can be helpful in several circumstances where making physical contact is undesirable, such as when the object is fragile, located in a dangerous area, or moving. It is helpful when a quick response is desirable, or when it is not possible to guarantee an excellent thermal contact between the object under test and the sensor. Moreover, the technique of measuring temperature without contact can be more accurate and yield results that are more reliable than contact temperature measurement methods.

The extremely small 3 x 3 x 1 mm³ QFN package of the Melexis MLX90832 is a full-solution device that incorporates the optics, a sensor element, digital signal processing, and digital interfacing, providing a quick and simple integration for a wide range of modern applications within a limited space.

With factory calibration, the MLX90832 offers high accuracy, while Melexis has ensured thermal and electrical precautions internally so that the device has adequate compensation when operating in thermally harsh external conditions. Internally, the voltage signal from the thermopile element undergoes amplification and digitization. After undergoing digital filtering, the raw measurement data resides in the RAM of the device. All the functions remain under the control of a state machine. An I2C interface makes available the results of each measurement conversion, while allowing access to the control registers of the internal state machines, the RAM for auxiliary measurement data and pixel readings, and the E2PROM for calibration constants, the trimming values, and other measurement/device settings.

CP Coolers for Storing Reagents

In analytical chemistry, various reagents are necessary to detect the presence or absence of a substance, or for checking the occurrence of a specific reaction. For identifying or measuring a target substance, medical and laboratory technicians need to use reagents that cause a biological or chemical reaction to occur. For instance, biotechnologists consider oligomers, model organisms, antibodies, and specific cell lines as reagents for identifying and manipulating cell matter. Such reagents, especially those that biotechnologists use, have narrow operating temperature windows and therefore, require freezing or refrigeration.

If kept at room temperature, these temperature-sensitive reagents may degrade, becoming contaminated by microbial growth, thereby affecting their testing integrity. Most of these reagents will degrade and deteriorate within hours if stored without proper and precise refrigeration. Moreover, some reagents will be negatively affected if the storage temperature is tool low, or if they are subjected to multiple thaw-freeze cycles. Precise monitoring and stabilization of temperature below ambient is critical for extending the life of reagents, ensuring the accuracy and reliability of medical and laboratory tests, and keeping replacement costs down.

Manufacturers are using thermoelectric-based cooling solutions for precise temperature control. These are solid-state heat-pump devices, moving heat via the thermoelectric effect. In operation, direct current flowing through the cooler creates a temperature differential across the module. This allows one side of the thermoelectric cooler to get cold, suitable for heat absorption, while the other side heats up, making it possible to dissipate heat.

In actual operation, manufacturers typically connect thermoelectric coolers to forced convection heat sinks on the hot side to help dissipate the heat to the ambient. The action is reversible, such as by reversing the current flow, the thermoelectric cooler can be made to heat the cold side. Adequate control circuitry and the dual capability of the thermoelectric cooler enables capabilities of precise temperature control in the unit.

Compared to regular technologies like compressor-based systems, thermoelectric coolers such as the CP10-31-05 from Laird Thermal Systems Solutions deliver accurate temperature control in a more compact, stable, efficient, and reliable package. No refrigerants are necessary for the operation, making them friendly to the environment.

Featuring no moving parts and solid-state construction, the CP series of thermoelectric coolers operate extremely reliably, with no noise, and at low power. Their small footprint allows designers to increasingly integrate them into various instruments with easy flexibility and because of their solid-state operation, they can mount them in any orientation.

The Laird Thermal Systems Solutions has designed their CP series as compact and rugged thermoelectric cooling products. They operate at higher currents, making them suitable for large heat-pumping applications like storage systems for reagents. Designers mount the CP series of coolers near the storage chamber for accurately and closely regulating the temperature within the reagent chamber. The CP series of coolers offer a direct-to-air configuration, with a maximum cooling power of about 125 Watts and a temperature differential of 67 °C at ambient temperatures of 25 °C.

The CP series of thermoelectric coolers are available in a wide range of capacities, shapes, and power ranges for meeting the wide range of requirements suited to reagent cooling.

Differences Between Brushed and Brushless Motors

Motors govern our lives in multiple ways. They are the basic machines assisting us from simple transportation to sophisticated movement of a large variety of tools. There are many types of motors, both for operating on alternating current and direct current supplies. Of the motors operating on direct current supplies, there are two major categories—brushed and brushless—with differences in their construction, structure, and operation affecting their performance.

Both brushed and brushless motors operate using the principles of EM or electromagnetic induction, converting electrical energy to mechanical rotary movement. Both types of motors allow electricity to pass through copper windings, thereby creating interacting electromagnetic fields that cause the rotor to rotate and produce mechanical energy. However, their design concepts are different, making them differ in performance, cost, and maintenance.

Of the two, the brushed motor is the older design, having been available for over a century. These have a simplistic structure with two coils, one on the stator and the other on the rotor. A pair of carbon brushes delivers power to the coils on the rotor. Typically, brushed motors have four major parts—stator, rotor, commutator, and brushes.

The stator is the stationary part of the motor. It contains the stator windings or permanent magnets. The rotor, as the name suggests, is the rotating part, attached to the shaft. It has several rotor coils that, when powered, create an electromagnetic field to interact with the EM field of the stator. The commutator is a sectioned metal ring to ensure each rotor winding receives power as it rotates. It helps in reversing the polarity of the current through the rotor windings every half turn of the rotor. Brushes are stationary carbon electrodes that feed power to the rotor windings through the commutator.

As current passes through the stator and rotor windings, depending on their relative positioning, their EM fields either attract or repel each other. This makes the rotor turn, and thereby, changes the commutator connection to the brushes. The current flow now passes through a newer rotor coil and propels the rotor further in the same direction as before. This goes on until the rotational friction balances the EM interaction, at which point the motor’s rotational speed stabilizes.

Once transistors became more common in electronics, brushless motors started gaining popularity. Brushless motors also have four major parts—stator, rotor, sensors, and control circuits. Here too, the stator is the stationary part of the motor and has several copper coils, which, when powered, generate EM fields. The rotor is the moving part attached to the shaft of the motor. But rather than coils, the rotor has permanent magnets that generate their own EM fields. Hall-Effect type sensors sense the position of the coils with respect to the rotor magnets. The control circuit replaces the commutator and brushes to decide which coils in the stator should be powered next.

Brushless motors are more efficient as compared to brushed motors, and they provide higher torque, faster acceleration, lower noise, and lower maintenance. However, brushless motors are more expensive and heavier.

The Electronic Vampire Power Loss

As the use of smart electronic gadgets increases in our lives, we have grown used to having them available for use at any instant necessary. Nowadays, no one is ready to switch on a piece of equipment and wait for it to become operational—we need them instantly on and active. This functionality means the equipment must remain always on, consuming power.

However, this posed an additional problem for battery-powered equipment, as the always-on status drained batteries very fast. Therefore, the design of electronic equipment required a standby status, which reduced its power consumption to a substantially low level. This standby power loss is also known as vampire power loss.

Considering the total number of electronic equipment each one of us uses at home, at the office, on the move, etc., the total amount of vampire power loss is a substantial amount, enough to strain our infrastructure at the power level, while costing people and businesses lost money in wasted energy. This is largely on account of electronic devices being constantly connected and being on standby when not in direct use.

For instance, a legacy consumer product like a TV set, could consume upwards of several hundred dollars every year. Almost all modern products can waste money. That means an apartment building may be wasting thousands of dollars a year on products only waiting for their owners to use them. This not only affects operating costs but also impacts performance aspects like power factor corrections to every home.

Energy Star, an initiative of the US DOE or Department of Energy and the US Environmental Protection Agency program is addressing this issue. One can find the Energy Star label on over 75 certified product categories at homes, commercial buildings, and industrial plants. Another is the EU Directive 92/75/EC, which established a labeling scheme of energy consumption—mostly for white goods, cars, and televisions—that must display an EU Energy Label.

Design engineers are addressing this vampire power loss in two ways—a top-down approach, and a bottom-up approach. The top-down approach uses advanced circuit topology that is microcontroller-based. The microcontroller manages closely each on-chip peripheral and shuts down any unnecessary components like the display driver when entering standby mode. However, this strategy is useful in larger circuits, where there are many non-essential subsystems to be powered down when not in use.

Although the top-down approach is necessary and important, this is mostly a reactive approach. The method’s address of energy consumption is based on its power circuit. If the power circuit is not effective, the overall performance of the system remains limited.

On the other hand, the bottom-up approach begins with the power electronic components on the board. In this approach, operating at a higher efficiency level and using advanced subsystem power management has a much better effect when using a low standby power baseline. Using a system with better efficiency at its base level, the designer can effectively leverage several circuit-optimization methodologies. For instance, modern switching transistors offer performances that bring a cascading benefit to the rest of the subsystem.

Mass Manufacturing Micro-LED Displays

One of the challenges that industries and academic research groups occasionally face is that of transferring semiconductor devices of micrometer-scale from their native substrate to their respective receiving platforms. Now, researchers at the University of Strathclyde have successfully demonstrated a continuous roller printing process for picking up and transferring over 75,000 micrometer-scale semiconductor devices with very high accuracy, in a single roll. With this new method, the team has paved the way to creating a large-scale array of optical components that could be used for rapid manufacturing of micro-LED arrays.

According to the team, their unique printing process based on rollers is a way to tackle the above obstacle, and do so in a scalable manner, all the while meeting the stringent accuracy necessary for such an application. They claim their new roller technology is capable of matching the design of the device layout and has an accuracy of one micron or less. While the setup is inexpensive, it is also simple enough for users to construct it in locations with limited resources.

Large displays are made up of thousands to millions of tiny semiconductor devices. The real challenge was to manipulate these devices, such as taking them from their native substrate and placing them on the target substrate or circuit with high precision. The next hurdle was to inspect these devices, to ascertain their positional accuracy. For mass-manufacturing these displays, it is essential to not only effectively transfer them but also to find a way to look at them to assess their position and to effectively monitor the accuracy and yield.

As to how the transfer process works, the team explained that placing different materials in close proximity or in contact, develop interacting forces between them, generating adhesive forces between different material. The team uses this adhesion to pick up the devices and place them on the target surface. They use optical or adhesive coatings to enhance this adhesion, which makes the process easier.

Right now, the team is working to improve the accuracy of the printing process. At the same time, they are also trying to scale up the number of devices that the operation can transfer at a time. As the process works in terms of accuracy and yield, the team must further improve its scale and accuracy to be commercially viable.

The team is also working on a printing process for active devices. They intend to address individual microelectronic devices that they want to transfer and test such that they do not have any issues from the printing, either in the electrical or optical properties.

One of their biggest challenges is to effectively transfer a three-color display while maintaining good accuracy. The researchers feel their work will have an impact on the market and on the industry in general. By going ahead and overcoming the challenges, the researchers will need to find a method that is to a great extent compatible with the existing industry and manufacturing processes.

Micro-LED displays are making their way into cars for navigation systems, into AR and VR, in gaming monitors, and in the military for training purposes.

Stretch Your Battery

Although there is no existence of a stretchable phone or laptop at present, researchers have developed a prototype of a battery that is wearable and can be stretched. This stretchable Lithium-ion battery is fabric-based. With this type of battery, the team of researchers, from the University of Houston, has opened up a new direction for the future of wearable technology.

Professor Haleh Ardebili first came up with the idea for this stretchable Li-ion battery. He initially envisioned a future with smart, interactive, and powered clothes. From here, it was but a natural step to create stretchable batteries that could integrate with stretchable devices and clothes. For instance, one can use clothes with interactive sensors embedded in them to monitor their health.

Typically, batteries are in general rigid and are a major bottleneck in the wearable technology development of the future. Not only does the stiffness of a battery lead to limited functionality, but their use of liquid electrolytes raises safety concerns. Especially as the organic liquid electrolyte is flammable and prone to explosions. The researchers are using conductive fabric made of silver as the platform for the flexible battery and as the current collector.

The team prefers the woven sliver fabric for the battery, as it can easily deform mechanically by stretching, while still providing the necessary electrical conduction pathways for the electrodes of the battery to perform. The battery electrodes need to allow the movement of both ions and electrodes. With their experiments and prototypes, the researchers have entered to investigate an unexplored field in science and engineering. Going beyond the prototype, the researchers are working on optimizing the design of the battery, its fabrication, and its materials.

According to the researchers, the fabric-based stretchable battery will work wonders for various applications like smart space suits and devices for interacting with humans at a variety of levels, such as consumer electronic equipment embedded in garments for monitoring health. In fact, the applications for such a device are endless, providing a path for light, safe, flexible, and stretchable batteries. However, the team feels they have much to do before they can commercialize their idea.

While they need to work on the cost and scale for commercial viability, the team feels there is a clear need in the market for such batteries, especially in the future, for stretchable electronic devices. Once such products appear in the market, there will be a huge demand for the batteries. Right now, the team wants to make sure the batteries are as safe as possible.

The team faced many challenges in designing the stretchable battery. It took more than five years for them to reach the present state. Their main impediment was integrating the fabric with a functional battery.

As to how the battery works, the team explained that while the electro-chemically active material in the battery provides charge through bonding and debonding of lithium, it coats and deposits on the sliver stretchable fabric. While the lithium ions shuttle back and forth within the battery between the positive and negative electrodes, the battery can stretch as the polymer electrolyte and the fabric can also do so.

Basics of Potentiometers

The electronics industry uses many resistance-based components. While in some of them, the resistance is fixed, for others, the user can change the resistance. Potentiometers fall in the second category. Very often, they have a mechanical arrangement that allows the user to change the resistance value manually. Unlike the fixed resistor type components, potentiometers act as variable resistors.

The most common use of a potentiometer is to divide an applied voltage. Therefore, these components serve a dual purpose. On one hand, they help to adjust the voltage output within the circuit, while on the other, they can accurately measure the electric potential. This is the reason for their name being potentiometer. The typical construction of a potentiometer has a resistive element with a wiper. Adjusting the position of the wiper on the resistive element allows the potentiometer to deliver a continuously variable voltage output as a signal on its wiper. It is necessary to add that potentiometers are passive components. That means, unlike active elements, potentiometers do not require additional circuitry or a power supply to operate.

According to physical laws, the resistance of an object depends on many factors, one of them being its length. With all other parameters remaining constant, the resistance of an object will vary directly as its length does. Therefore, two objects made of the same material, with the same cross-sectional area, will exhibit different resistances if their lengths vary. Potentiometers take advantage of this principle to exhibit adjustable output.

The industry uses two types of potentiometers—analog and digital. Our focus is primarily on analog potentiometers, of which there are again two types—linear and rotary. Both rely on mechanical arrangements to manipulate and control the output.

A potentiometer, whether linear or rotary, has a sliding contact that the user can move along a uniformly resistive element. Altering the position of this sliding contact results in its adjustable output. The slider actually modifies the path through which current flows in the potentiometer. With the input voltage applied across the entire length of the resistive element, the output voltage is available as a potential drop between one end of the resistive element and the sliding or rotating contact. By adjusting the position of the moving element along the resistive element, it is possible to determine the voltage applied to the next part of the circuit.

As the name suggests, linear potentiometers employ a straight-line or linear motion using a sliding mechanism for establishing contact with the resistive element. The linear motion adjusts the contact’s position on the resistive element and subsequently, the output voltage.

On the other hand, rotary potentiometers use angular movement. They have a shaft connected to a wiper. This wiper slides along a resistive element arranged circularly around the shaft. By turning a knob on the shaft, it is possible to change the position of the wiper, thereby altering the output. Other variants of the rotary potentiometers are also available, where an external tool can rotate the wiper, thereby eliminating the need for a shaft to be present.

What is the Raspberry Pi Pico?

The electronic industry uses embedded systems with powerful, low-cost MCUs or microcomputer units. This helps product development by adding capabilities like machine learning and rapid prototyping while supporting many types of tests. In most cases, the designer must understand the MCU in depth while also mastering low-level programming languages. Often, development boards are way too expensive, not readily available, and it may be difficult to get them up and running. As an alternative, designers can go for the Raspberry Pi Pico.

The Raspberry Pi Pico is a readily available, low-cost development board. It uses the RP2040 MCU which offers a wide range of capabilities to the designer. Additionally, it has many extension boards and software development kits that make the task of an embedded system designer easy.

First introduced in 2021, designers can use the Raspberry Pi Pico as a standalone development board. They can also integrate the board into a system by soldering the edge connectors onto a carrier board. The Pico is popular mainly because of its sub $5 cost, which is way less than the $20+ price of other similar development boards.

The RP2040 MCU that the Pico uses is a dual-core processor of the ARM Cortex family. It operates at 133 MHz. It includes 264 kB of SRAM and an external 2 MB flash chip interfacing with the MCU over a quad serial peripheral interface. A user LED, pushbutton, and crystal oscillator are on the board. The user can configure the pushbutton to boot the processor directly or direct it to a bootloader. They can use the crystal oscillator to act as a PLL or phase-locked loop for creating a high-speed CPU clock.

The Pi Pico offers an extensive ecosystem, where developers can use either the C or the MicroPython language to write applications for the board. In reality, there are three types of Pi Pico boards to choose from—the SC0915 with a standard configuration, the SC0197 with the header connectors, and the SC0918 with a low-cost Wi-Fi chip.

Each of the above boards has the same general footprint. The edge connectors are 40-pins providing connection options for peripherals. Among the connections available are those for power, ground, UART or universal asynchronous receiver and transmitter, GPIO or general purpose input and output, PWM or pulse width modulation, ADC or analog to digital converter, SPI or serial peripheral interface, I2C or inter-integrated circuit interface, and debugging.

There are several options for using the Pi Pico for rapid prototyping. One can use a breadboard and populate the headers, but this may result in a mess of wires. The other neater option is to use breakout boards to expand the edge connectors and make them available for easy interfacing.

The Raspberry Pi Pico ecosystem offers MicroPython as an alternative to the older C language. This is a modern language that most designers are already familiar with. They use API or application programming interfaces for accessing hardware and abstracting out the low-level details of the MCU and its related hardware.